Application of chlorinated waste rubber as a flame retardant of low density polyethylene

For the reuse of the abundant waste rubber (WR), chlorinated waste rubber (Cl‐WR) was prepared by a water‐based chlorination method using chlorine gas as the chlorinating reagent. The resultant Cl‐WR was used as a flame retardant of low density polyethylene (LDPE) matrix. The properties of WR and Cl‐WR were characterized by thermogravimetric (TG) and Fourier transform infrared (FTIR) spectrometer. The results indicated that the Cl‐WR with a 42% chlorine content had a higher char residue than WR. The limiting oxygen index (LOI) value can be increased up to 27.2 and the flame retardancy reached to the maximum (V‐0) grade for the LDPE/Cl‐WR‐Sb blends with mass ratios of Cl‐WR/LDPE and Cl‐WR/Sb 2 O 3 being 80/100 and 1.5/1, respectively. The improvement of the flame retardancy and thermal properties of the LDPE/Cl‐WR‐Sb blends were attributed to the char formation and synergistic effect between Cl‐WR and Sb 2 O 3 in a high temperature region, although the mechanical properties of the said blend decreased in comparison with that of the neat LDPE.